[Melee] Vargouille’s Kiss (standard; only when the vargouille lover has combat advantage) Necrotic: +7 vs. Fortitude; 2d8+4 necrotic damage and target is stunned and immobilized (save ends both). If the target is killed by this damage, its head detaches as a new vargouille (of a type of the dm’s choice) in 1d6 hours.

[Melee] Double Smash (standard; at will): The girallon makes two smash attacks.
[Melee] Rending Crush (standard; recharges when first bloodied): The girallon attempts to use all four of its arms in a combined rend and crush. Reach 2; +35 vs. AC; 4d10+7 damage and the target is stunned (save ends).

Heck, since they're basically diseased goblins (with that lovely spatio-temporal thing), could just stat 'em up across a large range (like goblins)

And...with the whole "healing when struck" and can only be damaged by healing....and since 4e is all about exception-based design....let PCs blow healing surges during the encounter. It goes off in a "close blast 1" and deals XXX damage to the nilbog. Or something like that

These guys are obscure enough that I felt the need to put in a little bit of flavor text for them. Most of the things that I've been converting have no such need.

CHAGMAT
The chagmat are a race of hideous creatures that resemble upright spiders, with near-humanoid form. These terrifying monsters have warred on mammalian races, from orc to elf to human, and are known to suck the blood out of captive or slain humanoids. These terrifying creatures are without scruples or mercy; only by agreeing to help them gather more “food” can mammals hope to survive in an area ruled by chagmat.